6.12-stable review patch. If anyone has any objections, please let me know.
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From: Shyam Prasad N sprasad@microsoft.com
commit f1bf10d7e909fe898a112f5cae1e97ce34d6484d upstream.
The netfs library could break down a read request into multiple subrequests. When multichannel is used, there is potential to improve performance when each of these subrequests pick a different channel.
Today we call cifs_pick_channel when the main read request is initialized in cifs_init_request. This change moves this to cifs_prepare_read, which is the right place to pick channel since it gets called for each subrequest.
Interestingly cifs_prepare_write already does channel selection for individual subreq, but looks like it was missed for read. This is especially important when multichannel is used with increased rasize.
In my test setup, with rasize set to 8MB, a sequential read of large file was taking 11.5s without this change. With the change, it completed in 9s. The difference is even more signigicant with bigger rasize.
Cc: stable@vger.kernel.org Cc: David Howells dhowells@redhat.com Signed-off-by: Shyam Prasad N sprasad@microsoft.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/smb/client/cifsglob.h | 1 - fs/smb/client/file.c | 7 ++++--- 2 files changed, 4 insertions(+), 4 deletions(-)
--- a/fs/smb/client/cifsglob.h +++ b/fs/smb/client/cifsglob.h @@ -1476,7 +1476,6 @@ struct cifs_io_parms { struct cifs_io_request { struct netfs_io_request rreq; struct cifsFileInfo *cfile; - struct TCP_Server_Info *server; pid_t pid; };
--- a/fs/smb/client/file.c +++ b/fs/smb/client/file.c @@ -147,7 +147,7 @@ static int cifs_prepare_read(struct netf struct netfs_io_request *rreq = subreq->rreq; struct cifs_io_subrequest *rdata = container_of(subreq, struct cifs_io_subrequest, subreq); struct cifs_io_request *req = container_of(subreq->rreq, struct cifs_io_request, rreq); - struct TCP_Server_Info *server = req->server; + struct TCP_Server_Info *server; struct cifs_sb_info *cifs_sb = CIFS_SB(rreq->inode->i_sb); size_t size; int rc = 0; @@ -156,6 +156,8 @@ static int cifs_prepare_read(struct netf rdata->xid = get_xid(); rdata->have_xid = true; } + + server = cifs_pick_channel(tlink_tcon(req->cfile->tlink)->ses); rdata->server = server;
if (cifs_sb->ctx->rsize == 0) @@ -198,7 +200,7 @@ static void cifs_issue_read(struct netfs struct netfs_io_request *rreq = subreq->rreq; struct cifs_io_subrequest *rdata = container_of(subreq, struct cifs_io_subrequest, subreq); struct cifs_io_request *req = container_of(subreq->rreq, struct cifs_io_request, rreq); - struct TCP_Server_Info *server = req->server; + struct TCP_Server_Info *server = rdata->server; int rc = 0;
cifs_dbg(FYI, "%s: op=%08x[%x] mapping=%p len=%zu/%zu\n", @@ -265,7 +267,6 @@ static int cifs_init_request(struct netf open_file = file->private_data; rreq->netfs_priv = file->private_data; req->cfile = cifsFileInfo_get(open_file); - req->server = cifs_pick_channel(tlink_tcon(req->cfile->tlink)->ses); if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD) req->pid = req->cfile->pid; } else if (rreq->origin != NETFS_WRITEBACK) {